1. Field of Invention-
The invention relates generally to a system for correctly identifying the type of X-Ray exposure performed. More particularly, the invention concerns a system which permits the use of substances other than lead to correctly and permanently mark X-Ray films taken for diverse conditions and with differing intensities of radiation exposure.
2. Description of Prior Art and Background of Invention-
Roentgen or X-Ray examinations, particularly for medical purposes, require not only the name and other statistics of the patient, but often the position of the patient, times after injections, specific and particular views, respiratory states, identification of the technician and other pertinent information. This information is supplied by an identifying marker which is permanently imprinted on the developed X-Ray film with a negative shadow due to the obstruction or absorption of X-Rays.
In the past, a variety of marking methods have been used for such identification. Generally, these have consisted of stamped or cast flat lead pieces. The exposed lead pieces are usually stored in open boxes divided in cubicles and are removed manually by the technician. Some of them are embedded in plastic and partially encased in aluminum. Frequently a hole is fashioned at one end by which they are hung on hooks in a random fashion and without organization. This results in time lost searching for the correct marker. Another method uses a clip-marker combination attached to the periphery of an X-Ray cassette. At times these do not imprint on the developed film because of their peripheral position. Yet another uses powdered lead contained between plastic tapes on which symbols can be written. These are cut in any desired length and again are attached to the cassette by opaque surgical adhesive. On the back of the opaque tape the type of marker concealed by the tape is written in ink for identification purposes. These are adhered to random sites when not being used.
While some markers are clipped to the edge of the film cassette, the majority are taped to the X-Ray film cassette or on the X-Ray table. At times, the cassette is placed on a "Buckey-Tray" beneath the X-Ray table, which carries the film cassette behind (or underneath) the patient and permits repeated exposures, without raising the patient to remove the film.
There exists disadvantages to each of the describe marking objects and methods:
First and foremost, they require the use of inorganic lead which is a poisonous substance. The powdered lead tape, in particular, permits the dissemination of lead into the environment. This occurs when the tape containing the powdered lead is cut across in order to obtain a marker of 2-4 inches in length. In addition to its toxicity, lead deposits on film cassette holders and X-Ray tables, so that particulate lead matter causes artifacts which can appear on the exposed X-Ray film. The stamped or cast lead markers that are not encased in plastic continue environmental contamination. In addition, they are handled by unprotected personnel.
Secondly, the common lead markers which are embedded in plastic and encased around the periphery with an aluminum frame, are too thick to be used in a "Buckey-Tray" because they can be easily scraped off and lost in the X-Ray table mechanism. In addition, research reveals no evidence that lead does not leach through the plastic to present in molecular forms on the surface. The lead tape may also be lost in X-Ray tables, and this is more serious since manipulating it for removal can cause the powdered lead to be spilled on the worker and within the X-Ray table. Expensive and time-consuming efforts are necessary to remove the lost objects and clean up the powdered lead.
The United States Environmental Protection Agency through the Toxic Substance Control Act, has instituted a concerted effort to reduce human exposure to lead through regulatory authorities. Included as one of the four major efforts in this direction is to "encourage use of substitutes for lead." Other efforts to rid the environment of lead address mining, smelting, casting and forming of the material. (OTS Candidate Pollution Prevention Project-"Lead Pollution Prevention." Jun. 30, 1989 and "U.S. Environmental Protection Agency Strategy for Reducing Lead Exposures." Feb. 21, 1991).
The difficulties addressed by the present intervention have also been recognized by prior art as discovered by a pre-examination search. The most relevant references recognizing these concerns and disclosed by the search is U.S. Pat. No. 4,813,062 to Gilpatrick, M.W., entitled "Radio-opaque Marker and Method," which elucidates the potential health hazards of lead and utilized bismuth-trioxide (Bi.sub.2 O.sub.3) as an alternative to make a radio-opaque crayon marker for textiles. Similarly, U.S. Pat. No. 4,274,006 to Caine, R.D., entitled "Universal X-Ray Marker," discusses the health hazards of various lead X-Ray markers and attempts to circumvent such problems by making a paste of powdered lead and sealing it. There is no reference to the concomitant health hazards of mining, smelting and mixing the lead that are necessary to that invention.
A number of other problems with only partial solutions can be found in U.S. Pat. No. 4,953,193 to Robinson, N.L., entitled "Fastening Combination Having Special Utility in Affixing on X-Ray Marking Device to a Cassette Adapted to Hold X-Ray Film." He points out the disadvantages of using opaque masking or surgical tape to affix the identifying marker to the cassette, which tape prevents the technician from visually confirming the identifying character of the marker. The present invention overcomes this objection by simply using clear transparent surgical tape, which permits identification of the marker. In addition, when discussing dislodgement of an X-Ray identifying marker, he states: (Column 1, Lines 57-64), "This is specially a problem when the drawer opening is just barely high enough to allow the cassette to pass through the opening. That is, when the cassette drawer is being closed, a thick profile marker on top of the cassette face might accidentally contact the upper edge of the drawer opening and be repositioned or be completely dragged off of the cassette face." He describes a marker 0.18 inches thick with a gap between the marker and the cassette to facilitate grasping and repositioning. Both the thickness and the unattached periphery of such a marker would present an object that could be scraped off. The present invention demonstrates a marker 0.04 inches thick which is completely adherent all about the periphery of the marker for fixation to the cassette and has been demonstrated more difficult to be removed inadvertently from the cassette.
Further, Robinson describes attaching the marker to the cassette using the Velcro mechanism of loop and hook. Besides increasing the thickness of the marker beyond the original 0.18 inches, the loops and hooks collect threads, lint and other debris which are extremely difficult to remove and may result in artifactual problems on the exposed X-Ray film. Again, the present invention solves these problems by using clear tapes which tapes can be renewed with minimal effort and expenditure of time, should they lose adhesion or become soiled.
In U.S. Pat. No. 3,573,455 to Suierveld, J., a brass template with precisely drilled holes was used to mask the x-rays impinging on a photographic film. After such exposure, the template was removed and another exposure made of the article to be analyzed. In that context, the template was used to assure precise spatial orientation of an article during X-ray photography. This invention utilizes the template concept only as a means of efficient manufacturing X-ray markers of the same size with different information. These markers are totally removed from the template and used repeatedly for identification purposes. The periphery of the template is then discarded. Malmud, H. et al U.S. Pat. No. 4,788,707 shows a tool comprised of plastic, lead, and aluminum which was designed to indicate the correct x-ray dosage for a given matter. They also refer to a step-wedge of increasing thicknesses to measure radiation dosages. The present invention describes markers of a constant thickness used only for the identification of the subject matter. By stacking these almost identical markers one on the other, the desired imprint on film can be achieved with almost any degree of radiation.
An excellent overview of the techniques generally employed by X-Ray technicians can be found in U.S. Pat. No. 4,529,635 by Sheldon, A.D., which method, however, requires special equipment, is time-consuming and employs lead.
Other Patents referring obliquely, from the standpoint of the current invention, to X-Ray marking systems are: U.S. Pat. No. 4,127,774 to Gillen, J.; U.S. Pat. No. 4,698,836 to Minasian, J.L.; U.S. Pat. No. 4,194,122 to Mitchell, E.C., Mitchell, C.J.; and U.S. Pat. No. 2,433,480 to Rendick, R.A.